How can I get the separated registry of my own among the share of three?

Situation : I belong to Hindu family. We are three real brothers. We have a registry of our house (in Lucknow) having names of all three. But the particular portion of the share is not divided. They are using our portion or I said the whole area by building additional rooms, toilets, and stairs etc. Now I want my separated registry of my own among the share of three. How can it be done?